The invention relates generally to a cleaning material that can be used to clean a printing machine, and more particularly to a cleaning material in the form of a fabric impregnated with a cleaning composition.
One of the more common printing techniques is offset lithography printing. In offset printing, an ink roll transfers ink to a plate cylinder. The plate cylinder typically contains lithographic plates that are wrapped around the circumference of the cylinder. After the lithographic plates contact the ink roller, the plate cylinder then transfers the inked impression onto a blanket cylinder. The blanket cylinder is typically made of a soft material such as rubber. The blanket cylinder transfers the inked impression to a printable surface such as a continuous web of paper. In a blanket-to-blanket press, the paper web is fed between two blanket cylinders so that both sides of the paper are printed at once.
During the printing process, ink, dirt, and other residues may accumulate on the blanket cylinders. The accumulation of such residues can cause various problems, such as poor print image quality and damage to the blanket. Additionally, the blanket cylinder should be cleaned when the plates on the plate cylinder are changed.
Traditionally, when a printing press needed cleaning, the press would be taken off-line and the equipment would be hand cleaned with solvents. Hand cleaning the printing press has several disadvantages. Hand cleaning can be labor intensive and possibly very time consuming, which could result in the printing press having to be off-line for a significant amount of time.
Several automated systems have been developed to improve printing press cleaning, reduce the amount of solvent consumed, and to lessen the amount of printing press downtime. Typically, these systems involve the use of a cleaning fabric that has been impregnated with a cleaning composition. The cleaning fabric is usually applied to the rollers and cylinders under tension or pressure so that the cleaning fabric has adequate contact with the surfaces that are being cleaned. The cleaning fabric can be unrolled from a roll and directed into contact with the blanket surface. The used portions of the fabric are then typically rolled onto a separate uptake roll for later disposal. Cleaning fabrics of this type are described, for example, in U.S. Pat. Nos. 5,368,157 and 6,263,795.
The cleaning compositions are typically comprised of low volatility organic solvents that are designed to remove inks and other residues from the surface of the blanket. Typically, solvents having higher volatilities are more effective in removing ink from the blanket. As a consequence, performance can be sacrificed because of the desire to use a solvent that will not quickly evaporate under ambient temperature and pressure. In some cases, the cleaning composition can also deteriorate the surface of the blanket.
Although current cleaning compositions have enjoyed widespread use in the cleaning of printing presses, there exists a need for an improved cleaning fabric having a cleaning composition that has excellent cleaning performance, low volatility, and does not adversely affect the blanket.